In a radio transmitter, the back-end is generally defined as the portion of the transmitter that sits between the digital baseband system and the antenna. The back-end includes an up-converter for up-converting a baseband signal received from the digital baseband system to a carrier frequency, a filter for filtering the up-converted signal, and a power amplifier for boosting the strength of the up-converted signal before it is transmitted by the antenna. In addition to the above mentioned components, the back-end includes a digital-to-analog converter (DAC) at some point before the antenna to convert the signal to be transmitted from a digital signal to an analog signal.
To take full advantage of continuing reductions in the size of integrated circuit (IC) process geometries, the DAC should be placed as close as possible to the antenna such that as many components as possible in the back-end can be implemented using digital circuitry. The reason being is that digital circuitry scales better in terms of cost and power with reductions in IC process geometries than analog circuitry. Although digital circuitry scales better, conventional digital implementations of many of the components in the back-end using currently available IC process geometries can still consume more area and/or power than their equivalent analog implementations, especially when operating at frequencies in the RF range. This can be a significant drawback for small, battery powered communication devices, such as mobile phones, laptops, tablets, smart watches, etc.
The embodiments of the present disclosure will be described with reference to the accompanying drawings. The drawing in which an element first appears is typically indicated by the leftmost digit(s) in the corresponding reference number.